WHAT IS API? 1

 

APIs are standardized ways to communicate between different software languages ​​and platforms. In this way, developers can access certain functions of another software and use them in their own applications. For example, a website's API may provide access to data on the website by another application.

The main purpose of using API is to easily and quickly meet remote data and information requests by making all or some methods of an application available to other applications. Thus, allowed remote users will be able to benefit from the transactions taking place in a single application, thanks to certain parameters. API generally serves to process real-time data one by one. The server processes the input with or without parameters sent by the server via JSON or XML API and returns a result set or just a success notification. Updates to be made only in a certain part of the data require a parameter. API ensures that these transactions are both fast and practical.

 

 

HOW DOES THE API WORK?

The way the API works is as follows.

• The receiving program makes a request (API Call). This request is processed as the actual request to the Web server via the URI.

• Once the request is received, the API calls the external program or web server.

• The server sends the requested information as a response to the API.

• API transfers the data it receives to the receiving program making the request.

What is the working logic?

To use the API, you may first need to obtain the API's access key. An access key is an authentication method used to access APIs. You can then access whatever features the APIs provide by making an HTTP request to a specific URL of the APIs. Briefly, the process that will occur is; The expected task is done by specifying the desired resource and HTTP method (GET, POST, PUT, DELETE, etc.). The API response usually comes in a data format such as JSON (JavaScript Object Notation) or XML (Extensible Markup Language). These data formats enable applications making API requests to easily process the API response.

 

Using APIs, application developers can access certain functionality of another application and use it in their own applications. For example, an e-commerce site can make payments using the API of a payment gateway or display map data using the API of a mapping service.

When using APIs, it is important to remember that the API may have certain limitations or fees. Additionally, when using the API, it is important to follow security protocols to ensure the correct use of the service offered by the API.

WHAT ARE THE API TYPES?

There are different types of APIs according to their intended use and architectural structure.

API Types According to Purposes of Use;

1. Open API: These are APIs that are accessible to everyone. These APIs often provide publicly available data that developers can use in third-party applications. APIs of social media sites can be given as examples. Open APIs are important for improving application ecosystems and allowing developers to create new applications.

2. Private API: These are APIs that are accessible only to a certain user group. Such APIs are used to enable the creation of in-house applications. An example is an API that allows a company's employees to access applications only within the company.

3. Internal API: These are APIs used to enable interaction between certain components of a software product. Such APIs allow certain components of the software to communicate with each other. An example is an API that a web application can use to communicate with the underlying database.

API Types According to Architectural Structure;

REST API: REST API, which stands for Representational State Transfer, is an API service that works using the HTTP protocol. It is an architectural model that enables data exchange between Server and Client. Rest API is the application interface that enables data exchange between web services using the Rest architecture.

It uses certain functions like GET, POST, PUT, DELETE from HTTP requests. REST uses JavaScript Object Notation (JSON) as the data format.

REST is a form of architectural pattern frequently used to create modern web-based applications. Being very useful, easy to maintain, easy to integrate and lightweight have made it one of the most preferred API types.

REST API simplifies the design of web services and works with a wide range of platforms and programming languages ​​because it is compatible with widely used standards such as HTTP.

How Do REST APIs Work?

• The client sends a request to the server using the API. That is, it communicates with the server.

• How the client will use the REST API is explained in the API document of the server applications.

• The server reviews the client's request and accepts the confirmation.

• The server acknowledges and processes the request.

• The server sends a response to the client. The response contains the information the client needs. Thus, the process is completed perfectly.

What are the REST API Features?

REST architecture is built on 6 items.

1. Stateless: Thanks to the stateless structure, you do not need to do a retrospective scan and there is no obligation to keep a record between each reguest.

2. Uniform Interface: This constraint is provided by the principles determined for the communication between the client and the server.

3. Cacheable: The client can create a cache mechanism according to the information sent.

4. Client-Server: According to this restriction, the client is responsible for storage operations etc. that are under the responsibility of the server. He doesn't care about things.

5. Layered System: Client-server architecture does not always mean that the client sends a request directly to a server and receives a response from it. At this stage, there may be layers such as security layer and cache layer.

6. Code on Demand: Code on demand constraint covers the ability of the server to send executable scripts and applets to the client in certain situations.

 

Advantages and disadvantages of REST-API

ADVANTAGES;

• Wide language and platform support: Thanks to its compatibility with different software languages ​​and platforms, more flexible and customizable applications can be developed.

• Easy integration: Since REST-APIs work over the HTTP protocol and support common data formats, they can be integrated quickly and easily.

• Efficient and scalable: Thanks to their stateless and layered structure, REST-API-based systems can be used on a large scale and resource usage is optimized.

• Well documented and community support: Thanks to the wide use and spread of REST-APIs, there is rich documentation and active community support.

• Independence: REST treats the server and client as independent entities. The communication between the server and the client is independent, and with each request by the client, all necessary information is transmitted to the server. This makes it easier for the server to scale without having to store client state.

• Extensibility: REST APIs are easy to add new resources and extend the API. Adding new resources does not complicate the API because each resource has its own URI.

• Scalability: REST APIs offer a structure that is easy to scale. This is suitable for serving large data streams and high-traffic applications.

• Statelessness: Since REST handles each request independently, it does not require operations such as session management on the server side. This allows the server to use less resources.

DISADVANTAGES;

• Performance problems: Especially in large and intensive data transfers, REST-APIs may experience performance problems due to the limitations of the HTTP protocol.

• Over-fetching and under-fetching: In REST-API requests, the problem of sending more or less data than the requested data may occur.

• Enterprise Security: REST API handles security issues in a specialized way, so it may sometimes require additional work to meet enterprise security requirements.

• Complexity Management: In large and complex applications, RESTful APIs can be difficult to manage and document.

• Lack of Standards: REST offers flexibility in many aspects, but this can lead to lack of standards and consistency issues between different applications.

• Performance: REST may sometimes not be as lightweight as SOAP in applications with a lot of data traffic. REST APIs may require more bandwidth and resource usage, especially if there are large data movement requirements.

SOAP API:

SOAP (Simple Object Access Protocol) is a simple object access protocol. It is used to access web services over HTTP. It is XML based. It was developed as an intermediate language so that applications created in various programming languages ​​can communicate with each other effectively. Web services use SOAP to exchange XML data between applications. SOAP supports both stateful and stateless operations.

When used as a web service architecture, SOAP performs communication between a client and a server. The client creates a SOAP message and sends it to the server. The server receives the message, creates a response, and sends it back. SOAP provides more security features compared to REST, but is heavier and less scalable.

SOAP provides a standardized way to represent data and call methods or functions remotely. It formats messages using XML and ensures the transmission of data that can be easily understood by different systems. SOAP messages are typically transmitted using Hyper Text Transfer Protocol (HTTP) or other application layer protocols.

The main components of a SOAP message include the envelope, header, and body. The envelope encapsulates the entire SOAP message and contains information about the message structure and processing instructions. The header is optional and may contain additional information such as authentication or encryption. The body contains the actual data or the method being called.

SOAP supports various communication patterns such as request-response, unidirectional or multicast. It also provides flexibility with the ability to carry application-specific information via headers.

One main advantage of SOAP is that it supports advanced features such as security, reliability and transaction management. It includes built-in mechanisms for features such as authentication, encryption, and error handling. These features make SOAP a preferred choice for enterprise applications that require robustness and compatibility with each other.

However, SOAP is more complex and heavy than other alternatives, especially REST. It requires more workload due to the XML-based message format and the additional processing required to parse and interpret the messages.

In general, SOAP is a protocol designed for structured and reliable communication between distributed systems. It has been widely used in enterprise scenarios and web services, especially where advanced features and compatibility are important.

For example, a SOAP request might look like this:

<SOAP-ENV:Envelope
    xmlns:SOAP-ENV=”http://schemas.xmlsoap.org/soap/envelope/”
    xmlns:example=”http://www.example.com/namespace”>
    <SOAP-ENV:Header>
        <example:Authentication>
            <example:Username>user123</example:Username>
            <example:Password>pass456</example:Password>
        </example:Authentication>
    </SOAP-ENV:Header>
    <SOAP-ENV:Body>
        <example:GetUserInfo>
            <example:UserID>12345</example:UserID>
        </example:GetUserInfo>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

This example represents a SOAP request to retrieve a user's information using a service with the “http://www.example.com/namespace” namespace. While authentication information is included in the header section, the user ID is stated in the body section.

Once this request is sent to a SOAP server, the server processes the request, performs the necessary operations, and returns a SOAP response as a result.

ADVANTAGES OF SOAP

Platform Independence: SOAP is a communication protocol that can work across different platforms and languages. This makes it easier for different systems to communicate with each other.

Security: SOAP supports layers of security and provides encryption, authentication and authorization of messages. For this reason, it is preferred in applications where sensitive data must be transmitted.

Transaction Oriented: SOAP is a transaction-oriented communication protocol. The client asks the server to perform a specific action and the server performs that action. This makes certain operations useful for certain results.

Extensibility: SOAP makes it easy to add new headers and features. This provides adaptability to meet the specific requirements of certain use cases.

Language Independence: SOAP is independent of the languages ​​used in communication. This offers the ability to communicate between applications written in different languages.

DISADVANTAGES OF SOAP

Complexity: SOAP messages are in XML format, which can cause textual complexity. This can lead to more bandwidth being used when greater data sharing is required.

Performance: SOAP may require more processor and bandwidth resources compared to other lighter-weight communication protocols, especially REST (Representational State Transfer). This may be disadvantageous in terms of performance.

Human Readability: XML-based SOAP messages are human readable but contain more characters than other data formats. This may cause data migration to require more resources.

Lack of Standard Application: In some cases, there may be a lack of standardized approaches in the use of SOAP. This may require application developers to create custom solutions for each situation.

Increased Development Time: SOAP can increase application development time compared to lighter communication protocols such as REST. Complexity and specific requirements can impact the development process.

WHERE TO USE?

SOAP is a communication protocol used in web services. SOAP messages are sent in an XML-based format. SOAP provides a secure and reliable way to communicate between applications running on different platforms and languages.

Some common uses of SOAP:

Web services: SOAP is used to create and consume web services. Web services are a way to exchange data and services between different applications.

Business integration: SOAP is used to exchange data and services between different business systems. This can help businesses operate more efficiently and effectively.

Mobile applications: SOAP is used to use web services for mobile applications. This allows mobile applications to access the functions and data provided by web services.

Examples showing how SOAP is used:

Ordering a product using a web service: A user can send SOAP messages to order a product using a web service. The web service uses SOAP messages to process the order and send a response to the user.

Sending customer information from one business application to another: A business application can use SOAP messages to send customer information to another. This can be used to centralize customer data in one place and keep it updated.

Sending location information from a mobile application to a web service: A mobile application can use SOAP messages to send location information to a web service. The web service may use this information for services such as maps or navigation.

These examples show just a few ways how SOAP can be used. SOAP is a powerful and flexible communication protocol for a variety of applications.

SOAP sample codes SOAP Request Example: Below is an example of a SOAP request. This example aims to send a city name to a weather service.

SOAP Fault Response Example: SOAP may also include an error response for error handling.

The features of SOAP can be listed as follows:

SOAP is a completely XML based protocol, data formatting is XML. Therefore it is easy for the developer to understand.

It is a platform independent protocol.

It is an open standard protocol so anyone can use it.

XML is an extension of the HTTP protocol for messaging.

SOAP messaging is useful for broadcasting messages from one computer to other computers.

It is possible to implement client-server architecture. The client can invoke a remote procedure call located on the server side using the SOAP protocol message.

SOAP provides data transfer for web services.

SOAP works by sending an envelope containing information about what needs to be done with web services.

A typical SOAP envelope contains a header and body, which contains a WSDL (Web Service Definition Language) file. This entire envelope is sent to the service provider, so SOAP needs larger bandwidth.

Let's examine the structure of the SOAP message in more detail:

A SOAP message; is encoded as an XML document containing an optional element and a required element. The element in is used to report errors.

SOAP Envelope is the root element found in every SOAP message and contains two subsets, an optional element and a mandatory element.

SOAP Header is an optional child element of the SOAP envelope structure and is used to convey relevant information to be processed by SOAP nodes along the message path.

SOAP Body is a mandatory sub-element of the SOAP envelope structure, which contains information about the final recipient of the message.

SOAP Fault is a child element of the SOAP body used to report errors. SOAP fault codes:

Sender: The problem was caused by incorrect or missing data from the sender.

Receiver: The problem was caused by a problem on the receiver side.

VersionMismatch: Indicates that the node does not recognize the SOAP version used.

MustUnderstand: Indicates that the node does not recognize a block marked with mustUnderstand.

Subcodes: Specifies error codes that can be nested up to 3 levels.

Reason: Contains human-readable (explanatory, understandable) explanation.

Difference Between Rest and Soap

Security: While providing security on SOAP can be easier and faster, this can be complicated for REST. When it comes to security for REST, it is a little weaker than SOAP.

Data Structure: While we can work with JSON, XML and even TEXT with REST, we should use XML with SOAP. In this way, REST can be more useful. With JSON, you can perform operations with smaller data sizes. If data sizes are important for your application, using REST will be suitable for you.

Application Speed: If you want your application to run faster, it will be beneficial to use REST.

Support: Developer tools for SOAP are better. We can find more resources to help us use. Documentation of REST is less than SOAP.

The REST approach works using HTTP methods. GET, POST, PUT, DELETE etc.

SOAP services use the RPC (Remote Process Call) working method, include security protocols such as WS-*, and store state information in requests and responses.

REST architecture is quite flexible and lightweight compared to SOAP, the amount of data carried is less, and its integration is easier

JSON (JavaScript Object Notation) and XML (eXtensible Markup Language) are data formats used to exchange information between different services or programs. Both can be read and written by us humans or machines. While JSON is a format in which data is grouped in key-value pairs, XML groups data in tags and creates a tree-shaped structure. JSON is lighter and faster, but is only suitable for simple data structures, while XML is used for more complex data structures.

What are the similarities between SOAP and REST?

You can use many different programming languages, architectures and platforms to create applications. It is very difficult to share data between such various technologies because they have different data formats. Both SOAP and REST are a product of efforts to solve this problem.

You can use SOAP and REST to create APIs or communication points between various applications. The terms web service and API are used interchangeably. But APIs are a broader category. Web services are a special type of API.

Other similarities between SOAP and REST include:

Both define rules and standards for how applications create, process, and respond to data requests from other applications

They both use HTTP, the standardized internet protocol, to exchange information

Both support SSL/TLS for secure and encrypted communication

You can use SOAP or REST to create secure, scalable, and fault-tolerant distributed systems.

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